Thanks for the offer, but I'm not going to stress over a rip on the cover to the point where I need a new copy.

I'd just like to know if gluing it to the cover in this way can be avoided in future.

I think the glue has changed or is very variable. In the past it has simply peeled off. Recently, however, it seems to be stickier. A few issues back it was so sticky I couldn't get all of it off the disc cover. When stuck to the inside pages, it tends to rip them. The cover is the ideal place to stick the disc, but if that glue must be used, I'd rather it wasn't stuck to anything I'd want to read.